Excessive lighting is a drain on resources and can render the world topsy turvy, making night into day, but it also turns out that not turning the lights out can have other far reaching effects.
Some years ago I worked for a stint on Norfolk Island, a small area of land surrounded by a big expanse of empty ocean. The island had no traffic lights and just one street light that I recall, and to walk after dark on a cloudy night was a sensory experience that I have never experienced before or since.
It was intensely dark. So dark you literally couldn’t see your hand in front of your face, let alone your feet or where you were going. It wasn’t a darkness that your eyes adjusted to, it was the kind of darkness that comes from the complete absence of light, only relieved when a farmhouse emerged around a bend or over the crest of a hill.
It’s unusual to experience that kind of darkness, especially in the city where the glow from street lights and office buildings continually illuminate the night sky. It’s not only in the city where the effects of light pollution can be observed, as sky’s can be brightened up to 100km’s away from illuminated centres. As a result heavily populated land masses, like Europe, have darkness levels some 2 to 4 times brighter than they would be naturally.
In fact, artificial illumination of our nocturnal landscapes is so commonplace that it interferes with astronomical observations, disrupts eco-systems and has been attributed to adverse health effects. Lighting the night time world also uses large amounts of energy and financial resources, and according to the United Nations Environment Programme (UNEP) lighting consumes one fourth of all energy expended worldwide.
As if these aren’t enough reasons to rethink current lighting behaviour, it transpires that the increase in light pollution is also directly linked to increases in atmospheric pollution. Scientific findings presented at the American Geophysical Union in San Francisco late last year showed that
light pollution hinders a nightly reaction that improves air quality.
During the darkness of night a natural form of nitrogen oxide, called the nitrate radical, works in the atmosphere to break down fumes from daytime pollutants and prevent the formation of smog and ozone. The nitrate radical is destroyed by the presence of sunlight so it is only at night that it performs this air cleaning magic.
However, as measurements taken by aircraft over Los Angeles have shown, levels of nitrate radicals are also diminished by the city’s after dark glow. Results showed that, although L.A’s lights were 10,000 times dimmer than the sun they were still bright enough to reduce nighttime cleansing of the air by up to 7% and increase the starting chemicals for ozone pollution the next day by up to 5%.
The research, which was carried out by the National Oceanic and Atmospheric Administration (NOAA) and the Cooperative Institute for research in Environmental Sciences (CIRES) in America, suggests that a reduction in light pollution would feasibly improve air quality. Of course, looking at ways to reduce the emission of pollutants in the first place is paramount, but the idea that it is possible to reduce air pollution by reconsidering how we light our darkness is one that can’t be overlooked. While many cities may be interested in this as a way to reduce high levels of ozone, even small improvements in air quality can be beneficial to health, and especially welcomed by allergy and asthma sufferers.
As the nitrate radical effect takes place not on the ground but in the skies above, a rethink of lighting design that contributes to sky luminance due to upward spill is the most immediate solution. While public street lighting in Australia is guided by standards addressing issues of glare and upward spill (AS1158), other light sources including advertising, corporate lighting, security lights and upward pointing floodlights are often poorly designed, without any consideration of how each might contribute to the overall incidence of light pollution.
Every year Earth Hour prompts us to turn off the lights as a way to take a stand against climate change, so it seems fitting to discover that the simple act of turning off the lights not only saves energy but has the potential to improve air quality and reduce ozone levels as well!
No wonder a trip to the country is so therapeutic. It really is the nighttime country air, working its scientific cleaning shift under a blanket of darkness, that makes us feel rested, healthy and ready for a bright, clean day.